1. Field of the Invention
This invention relates to an electrical junction box in which connectors are to be mounted which are used for connection of wire harnesses, and more particularly to an improvement of an electrical junction box which has a bolt-tightened multi-pole connector on a cover accommodating a circuit board.
2. Description of the Related Art
A conventional electrical junction box having a bolt-tightened multi-pole connector on a cover accommodating a circuit board will be described with reference to FIGS. 6 and 7.
In FIGS. 6 and 7, reference numeral 31 designates the conventional electrical junction box which comprises an upper cover 34, a lower cover (not shown), and a circuit board 33 interposed between those covers. The circuit board 33 is made up of an electrical insulating material, and has a plurality of bus bars 32 at suitable positions. The upper cover 34 includes a connector inserting section 35, which has an opening 37 surrounded by a frame 36. In the opening 37, a plurality of male terminals 38 are protruded.
A male multi-pole connector 39 is detachably inserted into the opening 37 of the connector inserting section 35. The male multi-pole connector 39 accommodates a plurality of female terminals which are connected to the ends of wires (not shown). A nut support 40 is provided at the center of the opening 37 of the connector inserting section 35, to support a nut 41. On the other hand, a receiver 42 adapted to receive the nut support 40 is provided at the center of the multi-pole connector 39, to support a bolt 43 which is to be engaged with the nut 41.
As was described above, the conventional electrical junction box 31 comprises the upper cover 34, the lower cover (not shown), and the circuit board 33 interposed between those covers. The male multi-pole connector 39 is fitted in the connector inserting section 35 formed in the upper cover 34. The bolt 43 in the male multi-pole connector 39 is engaged with the nut 41 in the nut support 40, so that the multi-pole connector 39 is fixedly secured to the electrical junction box 31.
When, in the conventional electrical junction box 31, the multi-pole connector 39 is fitted in the connector inserting section 35, the bolt 43 is threadably engaged with the nut 41. Hence, in this operation, part of the nut or bolt may be removed to form metal particles (hereinafter referred to as "scrapings", when applicable) 44 although the amount of the scrapings is considerably small. The scrapings may drop on the circuit board 33 for instance when the electrical junction box is vibrated. The scrapings thus dropped may bridge the bus bars 32 on the circuit board 33, thus short-circuiting the bus bars 32.
The above-described difficulty may be eliminated by employing the following method: No bus bars are arranged on the central area of the circuit board which includes the areas right below the bolt 43, and the bus bars are arranged at sufficiently large intervals. However, this method results in an increase in area of the circuit board, and accordingly an increase in volume of the electrical junction box.
Furthermore, in the conventional electrical junction box 31, the circuit board 33 between the upper cover 34 and the lower cover may be oscillated sidewardly.